This invention relates to an improved ultrasonic flange radii transducer device, and more particularly to an improved transducer holder and mechanism particularly adapted for flange radii flaw detection or evaluation in radii non-metal composite, laminate materials.
Non-metallic materials such as synthetic resins, ceramics, and composite materials containing resins and non-metallic filaments are finding wider applications in rotating machinery components such as hot gas turbine engine components. Many applications include important separate and individual parts manufactured from the noted materials. Composite materials components may be produced by combining layers of the material with a bonding medium and then curing the final product without any or minimal forming pressure or force. As a result the final product may include undesirable voids in the material as well as some delamination. In components having a 90.degree. flange or other corner angle, imposed stresses in the innermost corner of the angle become significantly more critical, particularly if material in the corner region contains flaws such as voids and delaminations. Ordinarily this innermost corner of an angle section includes a raised band or layer of the material with a small radius of curvature surface providing a smooth transition surface between the intersecting or joining surfaces defining the angle or corner. These small radii curve surfaces sometimes referred to as fillets or fillet regions are predetermined in size and shape to counter the high stress concentration usually found where surfaces sharply intersect. Consequently a flaw in the noted innermost corner material or fillet region becomes even more critical as a source or cause of premature failure. Because of the required high degree of precision and quality of hot gas turbine engines and associated components, the noted parts and components with angled surfaces are usually subjected to close and comprehensive inspection, with the result that various testing devices and systems have been developed for their flaw detection. Ultrasonic flaw detection systems have been found favorable for such inspections. In such a system an ultrasound wave is projected perpendicularly into, for example, the surface to be inspected. The sonic wave penetrates the surface and passes through the material of the part being inspected. As the sonic wave passes through the part material, all or part of the wave is reflected by flaws such as inclusions and discontinuities within the material. These reflections are sensed by a transducer and electronically processed to provide a visual and/or recorded interpretation of the flaws. Effectiveness of ultrasonic inspection systems as described is predicated on having a close coupling between the transducer and the inspecting surface, and having the projecting ultrasonic wave enter the surface in perpendicular relationship to maximize wave reflection and detection as well as the characteristics of a discovered flaw. In small radii surfaces such as the small radius interconnecting surface or fillet in the included angle between a pair of angled surfaces, a 90.degree. flange angle, for example, it has been difficult to provide means for continuously projecting an ultrasound beam radially and perpendicularly into the curved surface as well as incrementally and transversely along the curvature of the surface. It also has been a practice to provide sliding or rolling probes or transducers which move along the curved surface in contact relationship to closely follow the curve of as well as to provide close sound coupling with the surface. However, probes adapted to follow and couple with smaller radii curved surfaces represent a continuing problem of wave perpendicularity and close coupling. For this reason various ultrasonic devices and arrangements have been developed to obtain an optimum near perpendicular scan of small flange radii. In general these arrangements continue to include an ultrasound wave emitting transducer probe whether a rubbing probe, or a rotating ball or roller probe, together with appropriate mechanisms which attempt to couple, move, and guide the probe over the surface to be scanned while at the same time retaining a near perpendicular scan. Ultrasound coupling between the curved surface and the contacting probe, as well as obtaining a full and precise scan, together with real time display across the surface remain problem areas.